Mechanisms of Genetic Exchange

Question 1

where are the genes in the bacteria?

Answer 1

in the chromosome, in plasmids. plasmids carry unessential genes

Question 2

why is there a rapid rate of evolution?

Answer 2

high population density and fast growth rate

Question 3

what is transformation?

Answer 3

the process by which bacterial cells take up free DNA molecules, bringing about genetic change.

Question 4

which process set the stage for the discovery of DNA?

Answer 4

transformation

Question 5

what are competent bacteria?

Answer 5

cells capable of taking up DNA and being transformed

Question 6

how can you force cells to take up DNA?

Answer 6

electricity (electroporation)

Question 7

what is transduction?

Answer 7

transduction is the transfer of DNA from one cell to another by a bacteriophage. A virus is involved

Question 8

what are the 2 modes of transduction?

Answer 8

generalized transduction - any part of the host genome is packed inside the virion
- specialized transduction -DNA from a specific region of the host chromosome is integrated directly into the virus genome

Question 9

what are the 2 modes of transduction?

Answer 9

generalized transduction - any part of the host genome is packed inside the virion
- specialized transduction -DNA from a specific region of the host chromosome is integrated directly into the virus genome (Really effective and useful)

Question 10

steps of generalized transduction

Answer 10

1. we start off with a bacteria infected with a bacteriophage
2. bacteriophage DNA enters the cell
3. replication occurs, hot cells produces more versions of the pharge DNA
4. end up with many new bacteriophages ready to leave the cell
   5.however, one of the bacteriophages would have picked up the donor cell DNA due to random event in replication
5. that bacteriophage can now go on and infect another cell, so we end up with a transducing particle being incorporated in the next round of recombination
6. we then end up with a transduced recipient cell.
   this would be a generalised event

Question 11

what is bacterial conjugation?

Answer 11

mechanism of genetic transfer that involve cell to cell contact.
it needs a donor cell and a recipient cell, they need plasmids to mate

Question 12

what is the plasmid called in conjugation>

Answer 12

F plasmid, for fertility

Question 13

what are the requirements for conjugation to happen?

Answer 13

the donor cell must contain a conjugative plasmid, the bacteria must be in contact with each other

Question 14

what does the fertility plasmid contain?

Answer 14

contains the genes for the pilus, a pilus connects 2 cells

Question 15

what produces the pilus?

Answer 15

the donor cell, it is essential for conjugation

Question 16

what is a F plasmid?

Answer 16

a circular DNA molecule

Question 17

what does a plasmid contain?

Answer 17

contains genes that regulate DNA replication

Question 18

what are F+ cells?

Answer 18

cells that have the F plasmid but its not integrated into the host chromosome

Question 19

what are Hfr cells?

Answer 19

cells that contain the F plasmid and it’s integrated into the host’s chromosome. they are useful in the lab

Question 20

once the F plasmid is present, what happens?

Answer 20

a pilus is formed, dna can be transferred from one cell to another, the cell can no longer act as a recipient so its surface receptors alter

Question 21

how does bacteria produce insulin?

Answer 21

restriction enzymes chop up bacterial dna, use that to recombine with the human gene, then weve got e coli that can make human insulin